It is known in the art to place inflatable bladders in seats, such as automobile seats, and various seat components, such as head rests, for adjustably altering the surface contours of the seats in accordance with individual preferences. Of course, the change in surface contour is accomplished by selectively inflating one or more such bladders with air or other suitable gas. Typically such seat bladders comprise two, or more inflatable chambers, each chamber being defined by an inner and outer wall. The inner and outer walls of each chamber are secured together with adhesive or with a heat sealing process which secures the inner surfaces of the walls together, but leaves the perimeter edges of the walls unsealed and exposed. The chambers are joined by securing selected portions of their respective inner walls together utilizing an adhesive or heat sealing method. At a point where the inner walls are joined an opening is provided to establish fluid communications between the chambers and the wall edges circumscribing the opening are unsealed and exposed. Further, the preferred fabrication material for fabricating the inner and outer walls is a laminate, including a web or fabric layer sandwiched between layers of a plastic material. Typically the fabric layer is a synthetic or natural fiber and the plastic layers are made from polyetherurethane or other heat sealable material. This laminated material is favored because it is suitably flexable to allow inflation, and yet strong and durable. However, it has been found that when a bladder is inflated there is a tendency for air or gas to escape from the bladder by entering the thread paths of the fabric layer of the inner walls at the exposed edges circumscribing the opening between chambers and exiting the bladder via the exposed perimeter edges of the inner walls. Thus, over a period of time the bladder deflates and must be reinflated if the desired seat contour is to be re-established.
Therefore, it is an object of the present invention to provide an adjustable seat assembly bladder which is sealed to prevent loss of air or gas from the bladder through the laminated chamber walls, and to provide a method for accomplishing such sealing of the bladder.
It is a further object of the present invention to provide an adjustable seat assembly bladder sealing method which is inexpensive to practice and a seat bladder which does not require periodic reinflation to maintain the desired seat contours.